Recently, it is possible to display the desktop frame on a given computer on another computer through a network by using software such as VNC (Virtual Network Computing: AT&T laboratories in Cambridge), Microsoft's Remote Assistance, or IBM's Desktop on Call. Many of these software applications are designed to display a desktop frame on another computer while maintaining security by requesting a password at the time of connection and performing authentication (see, for example, Japanese Patent Laid-Open No. 2003-66826).
In addition, a character input technique called a virtual keyboard, screen keyboard, or software keyboard has recently been realized. For example, a PDA or the like often does not have a keyboard as hardware because of its physical limitation, and hence a virtual keyboard having character keys arranged on it is displayed on an LCD with a touch panel. Characters are input by operating this virtual keyboard. If a virtual keyboard is displayed on the display of a general personal computer having a keyboard as hardware, desired character keys displayed on the display can be selected with a mouse. This makes it possible to input characters by only mouse operation.
In general, a selected key is, for example, highlighted on such a virtual keyboard to allow an operator to easily check whether or not a correct key is selected.
If, however, a virtual keyboard is used while the desktop frame is disclosed to the outside, the highlighted display of a selected key is also seen on an external device. If an ordinary text is seen, no problem arises. If, however, the purpose of input is to enter a password, security cannot be guaranteed.